In optical, magneto-optical and magnetic disc drives used for data storage, an actuator arm positions read or write heads over the disc to acquire information from the disc or store information to the disc. Movement of the actuator arm is typically controlled by a magnetic motor that includes a conductive coil position between a magnetic assembly. Typically, the magnetic assembly consists of two magnetic pieces bonded to two respective backirons that are maintained a fixed distance apart so that the conductive coil can move between the magnets.
To ensure consistent and predictable actuator arm movement, each magnetic assembly must be constructed with extreme precision so that variations between magnetic assemblies are minimized. In particular, the magnets must be precisely positioned relative to their respective backirons so that the position of the conductive coil relative to the magnet is consistent in each disc drive.
This type of accuracy and consistency cannot be achieved without the use of bonding stations that clamp the backiron and the magnet in a desired spatial relationship during bonding.
To position the backiron relative to the magnet, many bonding stations use locating pins that resiliently pivot laterally to allow the backiron to be "snapped" into place over an already properly position magnet. Once the backiron is inserted over the magnet, the locating pins apply a lateral force to the sides of the backiron to keep it properly positioned over the magnet.
In light of the forces placed on the locating pins, the manufacturers of the pins suggest press fitting the pins into a pin holder so that the pins do not become dislodge from the holder. To accommodate press fitting, the manufacturer of the locating pins includes deformable ridges around the perimeter of the pins. Press fitting is accomplished by forcing each locating pin into an aperture that has a diameter that causes the ridges of the pin to deform as they come into frictional contact with the side walls of the aperture. This deformation frictionally connects each locating pin to the sidewalls of its respective aperture.
Although press fitting locating pins is recommended by the manufacturer and provides a strong connection between the locating pin and the pin holder, it produces several problems. Most notably, press fitting makes it difficult to replace the locating pins. The present inventor has recognized that because of the heavy use that bonding stations experience in a manufacturing setting, the resilient portions of the locating pins tend to deteriorate over time and must be replaced. However, with a press fit locating pin, the friction between the pin holder and the locating pin will not allow the pin to be withdrawn from the movable assembly simply by pulling on the protruding portions of the locating pin. Instead, the lateral actuator and the movable assembly must be removed from the base so that the locating pin can be pushed out by inserting a rod through a hole in the bottom of the pin holder.
The present invention addresses these and other problems, and offers other advantages over the prior art.